I do a lot of reading up of reviews from the likes of 'tyretest' etc before spending out.
Do keep an open mind on the public reviews like those though, as a new maker could easily get a few cronies to bump up the review count, and many of the comments on the German site are in different languages (obviously), but the scoring system is ok.
The various mags sometimes do good tests, but obviously these usually only cover a small percentage of whats available out there.
My number one priority is wet grip, and as such Chinese ditchfinders are out of the question.
I have found some very good alternatives to the mainstream over the years and Vredestein is one such (the wintrac has to be one of the best winter tyres available), also Nokian (difficult to source).
I've taken my Goodyear F1's off as fed up to the back teeth with having to drive 2 or 3 miles to get rid of the overnight flatspot, and the hopeless wheelspin when the tyres are cold.
Now on a set of Toyo T1R's on the ageing MB, so far so good.
By the way, i run winter and summer tyres/wheels , does anyone else bother?